How to coordinate Welding Arm and Positioner to move coordinated as correct weldspeed

TysonDeNobrega

Hi everybody!

Im trying to weld a flange on a pipe, pretty simple. However the flange is in the same plane as the positioner platter, rotating off center. Since I'm required to do a 1/2" weld I must angle the joint so I am "in position", ie rotate and hold axis one of the positioner at 45° while the elbow rotates off center of the flange in question. (Please see attached image). 

So far Im able to create the work-object connected to the positioner platter. I have the robot following the correct path but the speed the positioner moves is constant which is wrong. In order to keep the torch in the 1F position the positioner and robot need to move in-sync at variable speeds, and I'm a little lost. 

KgaOfflineCenter

Hi,

I believe constant speed of positioner is correct.

Do you want constant welding speed? If yes the rotation speed should be constant.

BR / Henrik

TysonDeNobrega

Yes, my goal is to have a constant welding speed, ie the tcp should move at a constant speed relative to the circumference of the pipe. The only way to achieve this (while staying in the 1F position) would be to have the positioner rotating at a sinusoidal speed. I'm ALMOST sure of this, but have been proven wrong many times before......If the pipe was centered on the axis of rotation then a constant positioner speed would work.

I can reason through this mathematically but solving it, then programming it seems daunting....there must be a better way!

Mattims

I haven't actually tried the exact motion you are trying (can't see the picture either), but I have welded items at different distances from the center of the positioner workobject in one motion (spiralling out from the center of the positioner to further away, with reducing positioner speed to maintain correct welding travelspeed). And the positioner and robot speed was automatically maintained as desired.

The rotation speed was worked out by the controller from the distance the TCP is from the center of the workobject and the weldingdata travel speed. So make sure all the positions your programming the robot to go to are in the positioner workobject. If you use positions that are not in the positioner workobject the robot just rotates the positioner at a constant speed to make them arrive at the endpoint at the same time.

KgaOfflineCenter

Hi,

I am thinking like this:

Let say the pipe is in the center, then the positioner will turn in constant angle speed.

Move the pipe off center. You still will turn the pipe 360 deg and to obtain constant welding speed the angle speed must be constant.

The difference will be that the robot has to compensate for the transform motion of the pipe. This will be automatic if using a coordinated workobject.

see film:

BR / Henrik

TysonDeNobrega

Very illustrative example Henrik.

I was wrong, i didn't account for the motion of the robot. Thank you very much for clearing this up!

KgaOfflineCenter

Thanks,

Good luck with the project!